I only installed a V2 with a pro mount included. Now, I bouhgt a used V1 and dont have any kind of backplate so I tought I needed one, so pro-mount what the easy way out.

Now the D-tek website tells me to do is to use those long screws with platic o-rings, without no backplate.... Anyone had experience with this ? Maybe I could build it like that.

If it's just a backplate you need, you can get away with the Thermalright bolt-thru mechanism since it incldue a backplate which fit the threading of the screws perfectly. No need to buy a pro-mount just for the backplate.